Pipe-cleaning device

ABSTRACT

A pipe-cleaning device ( 1 ) comprising a cutting head ( 2 ) for cutting away material on the interior of a pipe, a body ( 111 ) on which the cutting head is rotatably mounted and drive means ( 3, 4 ) for driving the rotation of the cutting head ( 2 ) with respect to the body ( 111 ). In a first aspect the cutting head ( 2 ) is provided with one or more inwardly collapsible cutting elements ( 21 ) and the body ( 111 ) has a plurality of arrays of inwardly collapsible support elements ( 30 ) extending in longitudinal direction of the body ( 111 ) for supporting the body ( 111 ) on the interior of a pipe. In a second aspect the cutting head ( 2 ) comprises at least one first collapsible cutting element ( 21 ) which extends radially from a rigid central part ( 11 ), ends in a first cutting block ( 22 ) and is provided with at least one mass increasing element ( 22 ) at an intermediate location. In a third aspect, the drive means comprise a stator ( 3 ) and a rotor ( 4 ), the stator having at least one nozzle ( 7 ) for directing a liquid stream successively onto a plurality of drive elements ( 5 ) of the rotor ( 4 ), the at least one nozzle ( 7 ) extending substantially within a plane (V) perpendicular to the rotation axis ( 9 ) of the rotor and being located inwardly from the rotor ( 4 ).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a pipe-cleaning device comprising arotatable cutting head for cutting away material on the interior of apipe, such as for example tree roots on the interior of a sewage pipe.The invention further relates to a cutting head mountable on apipe-cleaning device and a drive for driving the cutting head of apipe-cleaning device.

2. The Prior Art

From U.S. Pat. No. 5,713,093 a pipe-cleaning device is known whichcomprises a cutting head for cutting away material on the interior of apipe, a body on which the cutting head is rotatably mounted and drivemeans using a pressurized liquid for driving the rotation of the cuttinghead with respect to the body. The cutting head is made up of rigidcutting elements extending throughout the diameter of the device and thebody is circumferentially provided with rigid guide runners means forsupporting the body on the interior of the pipe to be cleaned.

The pipe-cleaning device known from U.S. Pat. No. 5,713,093 has thedisadvantage that it cannot be moved past certain obstructions which mayoccur in the interior of pipes. An example of such an obstruction is asubsidence of one pipe section with respect to an adjacent pipe section,which is for example common in sewage pipes. With the prior art device,there is a risk that the device comes to a standstill at suchobstructions.

The pipe-cleaning device known from U.S. Pat. No. 5,713,093 further hasthe disadvantage that the cutting head is unsuitable for cutting awaylarge obstructions.

Another disadvantage of the pipe-cleaning device known from U.S. Pat.No. 5,713,093 is that the amount of torque which can be developed forcutting away material from the interior of the pipe remains limited.

It is a first aim of the present invention to provide a pipe-cleaningdevice with which the risk that the device comes to a standstill atobstructions can be reduced.

It is a second aim of the present invention to provide a cutting headfor a pipe-cleaning device with improved cutting action.

It is a third aim of the present invention to provide a drive fordriving the rotation of a cutting head of a pipe-cleaning device withwhich the developed amount of torque can be increased.

SUMMARY OF THE INVENTION

According to the first aspect of the invention, the pipe-cleaning devicecomprises a cutting head with collapsible cutting elements and a bodywith collapsible support elements. The collapsible cutting elementsextend in radial direction of the cutting head and are inwardlycollapsible with respect to the circumference of the body on which thecutting head is mounted. The collapsible support elements are providedin a plurality of arrays on the body, each array extending oversubstantially the entire length of the body. The collapsible supportelements are inwardly collapsible with respect to the circumference ofthe body against the action of a resilient member.

The pipe-cleaning device of the invention is capable of passingobstructions like for example subsided pipe sections by thecollapsibility of the cutting elements on the head and the supportelements over the whole length of the body. In this way, the diameter ofthe pipe-cleaning device is variable over its entire length. However, ithas to be made sure that the body of the pipe-cleaning device issufficiently supported on the interior of the pipe, even if one or moreof the supporting elements have collapsed. This is achieved by arrangingthe supporting elements in arrays, so that the obstruction is taken byone supporting element after the other, and providing each element witha resilient member for counteracting the collapsing, so that afterhaving taken the obstruction the support element is returned to itsoriginal position. In other words, the supporting function of onesupport element is for a short while taken over by the other supportelements of the array.

The pipe-cleaning device of the first aspect of the invention preferablycomprises at least three arrays of at least three collapsible supportelements, the arrays being located at regular locations on thecircumference of the body. The device may however also be provided withany other number of arrays having any other number of supportingelements as deemed suitable by the person skilled in the art.

The collapsible support elements preferably comprise a wheel which isrotatably mounted on a collapsible arm, which is in turn pivotallymounted on the body. The rotation axis of the wheel is offset from thepivot axis in longitudinal direction of the body, so that thecollapsibility of the wheel is enhanced and it can be further ensuredthat the pipe-cleaning device does not come to a standstill at largeobstructions.

The resilient member is preferably a pull spring. The pull springpreferably extends in line with the collapsible arm in unloaded state.In this way, the pull force, which occurs when the wheel engages anobstruction and collapses and which pulls the arm and the wheel back totheir original positions, is small initially and increases as the wheelcollapses further. This helps to ensure that the wheel can collapse andis quickly returned to its original position afterwards.

Preferably, the collapsible support elements at the front end of thedevice, i.e. at the cutting head collapse in rearward direction whereasthe collapsible support elements at the rear end collapse in forwarddirection. This has the advantage that the first support element whichengages an obstruction always collapses in the opposite direction fromthe direction in which the pipe-cleaning device is moving, so that thedevice can easily be moved both forwards and backwards substantiallywithout risk that the device comes to a standstill or becomes stuck atobstructions.

According to the second aspect of the invention, the cutting headcomprises at least one first collapsible cutting element which extendsradially from a rigid central part. Each of these first collapsiblecutting elements ends in a first cutting block and is provided with atleast one mass increasing element at an intermediate location betweenthe central part and the first cutting block. With a mass increasingelement is meant that the mass of the collapsible cutting element at theintermediate location is higher than in between the intermediatelocation and the central part of the cutting head, or in between theintermediate location and the outer cutting block. Each collapsiblecutting element may be provided with one or more mass increasingelements, but for the sake of clarity only one mass increasing elementis used for the explanation below.

By providing the collapsible cutting element with the mass increasingelement, the kinetic energy of the chain during rotation is increased.This has the advantage that, when the outer cutting block strikes anobject, the cutting element will have less tendency to bend or tocollapse at the central part. The inertia of the cutting element at themass increasing element is increased, so that the bending will occur atthe mass increasing element. In other words, due to the mass increasingelement, the inner part of the collapsible cutting element between thecentral part and the mass increasing element will be disturbed to alesser extent than the outer part between the mass increasing elementand the outer cutting block. As a result, the cutting element can returnmore quickly to its desired fully extended position as a result ofcentrifugal forces, for again striking the object to be removed. Thisshows that with the cutting head of the second aspect of the inventionan improved cutting action can be achieved.

Preferably, the mass increasing elements form second cutting blocks, sothat they have a double function: avoiding undesired collapsing of thecutting element and providing cutting action at a shorter diameter fromthe outer cutting blocks. This can further enhance the cutting action.

The first collapsible cutting elements preferably comprise a first chainpart extending from the first, outer cutting block to the massincreasing element or second cutting block, and a second chain partextending from the mass increasing element to the central part of thecutting head. The weight of the first, outer chain part including thefirst, outer cutting block is preferably smaller than or equal to theweight of the second, inner chain part including the mass increasingelement. In this way, the disturbance of the inner chain part when theouter cutting block strikes an object is reduced to a minimum.

The cutting head preferably comprises at least one second collapsiblecutting element of shorter length at its front. More particularly, thelength of the second collapsible cutting elements, which also comprise achain part ending in a cutting block, is preferably substantially equalto that of the inner chain part of the first collapsible cuttingelements. Providing these shorter collapsible cutting elements at thefront has the advantage that the load on of the first collapsiblecutting elements is reduced, so that their bending towards the back canbe reduced. This can further improve the cutting action of the cuttinghead.

Any of the cutting blocks, whether at the end of the collapsible cuttingelements or at an intermediate location, may be provided with a cuttingprotrusion, which extends towards the front of the cutting head, forproviding additional cutting action.

According to the third aspect of the invention, the drive, which isprovided in the pipe-cleaning device for driving its cutting head,comprises a stator and a rotor rotatably mounted on the stator. Thestator has at least one nozzle connected to a supply duct, via which apressurised liquid is supplied, for directing a liquid streamsuccessively onto a plurality of drive elements of the rotor. Thenozzles extend substantially within a plane perpendicular to therotation axis of the rotor and is located inwardly from the rotor.

Since the one or more nozzles of the stator of the drive of theinvention are provided within the plane in which the rotor rotates, moreparticularly on its interior, the rotor is driven by forces which arelocated substantially perpendicular to its rotation axis. As a result,the driving forces are directed in the direction in which the driveelements of the rotor move during rotation. As a result, the torquewhich is developed by the rotor can be maximised.

Furthermore, by driving the rotor from its inside, the drive elements onthe rotor can be positioned as far as possible towards itscircumference, so that the torque arm is prolonged and the torque can befurther enhanced.

The drive plane of each drive element of the rotor is preferablydirected such that it receives the liquid stream in a substantiallyperpendicular direction. This means that the drive elements are orientedin such a way on the rotor, that the liquid streams hit them in asubstantially perpendicular direction and as much force as possible istransferred to the drive elements. In this way, the torque can befurther enhanced.

The drive planes are preferably directed in an angle α of 20-70°, morepreferably 30-60°, most preferably 40-50°, with respect to the circularpath along which they travel during operation. The nozzles arepreferably directed in an angle β of 45-90°, more preferably 60-80° withrespect to this circular path. The angles α and β may however also bewider or narrower.

Each drive element of the rotor has a leading edge which is rotatedfirst into the liquid stream of the nozzle during operation. Thisleading edge is preferably bevelled in a direction towards the driveplane of the in rotation direction previous drive element of the rotor.This has the advantage that the drive element forms less of anobstruction when it is rotated into the liquid stream and also that theliquid which is diverted by the previous drive element is lessobstructed. In this way, the friction losses can be reduced and thetorque developed by the rotor can be further enhanced. Furthermore, thereduced friction leads to less wear on the drive elements, so that thelife of the drive of the invention can be prolonged.

In order to reduce the pressure loss which occurs at the end of thenozzles, where the drive liquid leaves the nozzles and is urged onto thedrive elements, the distance x between the nozzle and the leading edgeof the drive elements is kept as low as possible. The distance x ispreferably between 1-5 mm, but may also be shorter or longer.

It is evident that the features of the first, second and/or thirdaspects of the invention may be combined in one pipe-cleaning device.

The invention will be further elucidated by means of the followingdescription and the appended figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic side view of an embodiment of the pipe-cleaningdevice of the invention, the collapsible cutting element being removedfor clarity.

FIG. 2 shows a schematic cross sectional view of the drive and thecutting head of the device of FIG. 1.

FIG. 3 shows a front view of a part of a collapsible cutting element ofthe cutting head according to the invention.

FIG. 4 shows a schematic cross section of the drive according to theinvention, taken along the line IV-IV of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The pipe-cleaning device 1 shown in figures is provided for cutting awayundesired material from the interior of a sewage pipe. To this end, thedevice 1 comprises a cutting head 2, which is rotatably mounted on abody 111 about a rotation axis 9. The cutting head comprises a rigidcentral part 11 and collapsible cutting elements 21 for removing theundesired material. In FIG. 2, the collapsible cutting elements 21 areonly partly shown. During operation, the device 1 is moved through apipe, of which the wall W is partly shown, in a forwards direction Z.

The device 1 is provided with a drive for rotating the cutting head 2.The drive comprises a stator 3 and a rotor 4. The stator comprises asupply duct 100 which can be coupled to a supply hose (not shown) forsupplying a pressurized drive liquid to the device. As shown in thefigures, the supply duct 100 ends in two branches 101 which extend inopposite directions and end in nozzles 7 at the circumference of thestator 3. The rotor 4 comprises a plurality of drive elements 5 or rotorblades, which are movable along a circular path around the circumferenceof the stator 3. Each of these drive elements 5 is provided with a driveplane 6 facing the stator 3.

The nozzles 7 of the stator 3 are directed such that during operationthe liquid, which is supplied via the duct 100 and branches 101 to thenozzles 7, forms liquid streams which drive the rotor 4. The directionof these liquid streams is shown by the arrows P. The drive elements 5catch each of the liquid streams successively, so that the rotor 4 isforced to rotate. It is remarked that the liquid streams themselves arenot shown; only the liquid flow is shown by arrows in the figures.

The rotor 4 is driven on its interior, namely by liquid streams whichare generated substantially within its rotation plane V. In this way,the liquid streams are in an optimal direction for driving the rotor 4and the drive elements 5 of the rotor are located further from therotation axis and as far as possible towards the pipe wall W, so that ahigh torque can be obtained.

The device 1 is provided with such a number of drive elements 5, thateach of the liquid streams substantially continuously contacts a driveelement 5. In this way, the liquid streams apply a substantiallycontinuous driving force to the rotor 4. The drive elements 5 arefurthermore directed in such a way with respect to each other, that theliquid which is diverted by the drive planes 6 can easily flow betweenthem. In order to reduce their obstruction of the liquid flow, theleading edges 8 of the drive elements are bevelled towards therespective previous drive element 5, so that the channel which isdefined by one drive plane 6 and a bevelled leading edge 8 hassubstantially parallel walls. The flow of the liquid from the rotor 4 isfurther improved in that the nozzles 7 are directed slightly towards therear end of the device 1, more particularly such that the direction P ofthe liquid streams forms an angle γ of 1-20°, more particularly 2-10°with the rotation plane V of the rotor 4.

The nozzles 7 are provided for directing the liquid streams in suchdirections P onto the drive elements 5 that they contact the driveplanes 6 in a substantially perpendicular direction. To this end, thenozzles 7 enclose an angle β of 45-90°, more particularly 60-80°, withthe circular path along which the drive elements 5 rotate duringoperation. The drive planes 6 enclose an angle α of 20-70°, moreparticularly 30-60°, or 40-50°, with this circular path. In this way,the liquid streams generated by the stator 3 can impart a large force onthe rotor 4, so that the developed torque can be maximized.

The distance x between the leading edges 8 and the nozzles 7 is kept asshort as possible for avoiding losses as a result of pressure drop whenthe liquid leaves the nozzles 7. To this end, the distance x is below 1cm and preferably 1-5 mm.

The operational pressure of the liquid supplied to the device 1 of FIGS.1 and 2 is 50-100 bar, but may also be higher or lower. The flow rate ofthe liquid is at least 50 l/min. The pressure and the flow rate areevidently chosen in function of the desired torque and rotation speed ofthe cutting head 2, which is preferably on the order of 5000 rpm.

The rigid central part 11 of the cutting head 2 of FIGS. 1 and 2 iswedge-shaped, for obtaining a cutting action when rotated at high speed.This central part 11 may however also have any other shape known to theperson skilled in the art. The central part 11 may also be removablymounted on the cutting head 2, so that it is interchangeable with othercentral cutting parts.

On the central part 11, one or more collapsible cutting elements 21 aremounted. In FIG. 2, one collapsible cutting element 21 is shown, butthere may also be less or more collapsible cutting elements 21. Thecollapsible cutting element 21 is a chain which is swung out by therotor 4 during operation, so that it extends radially and undesiredmaterial which is located in the pipe can be removed by the cuttingblocks 22 on the chain. These cutting blocks 22 can be provided with acutting protrusion for enhancing the cutting action. This cuttingprotrusion extends forwardly from the cutting block 22 and may be carvedor bevelled for avoiding a resistance build-up, which can be caused bycut material piling up at the cutting head 2.

The chain 21 comprises a plurality of cutting blocks 22, one at its endand at least one at an intermediate location between its and the pivotshaft 106 by which it is fixed to the cutting head 2. The cutting blocks22 at the intermediate locations form mass increasing elements, whichhave a higher weight relative to the chain links interconnecting thecutting blocks 22. In this way, the intermediate cutting blocks 22increase the inertia of the chain 21, so that when the outer cuttingblock 22 strikes an object, the chain 21 less disturbed and soonerreturns to its fully extended length.

The chain parts are preferably constructed such that the mass of thechain increased towards the central part 11 of the cutting head. Thismeans that the chain part including the outer cutting block preferablyhas a weight below or equal to that of an inner chain part including theintermediate cutting block.

As shown in FIG. 2, the chain 21 may comprise a frontal cutting elementof a shorter length, which may be fixed to the chain or not. Thisshorter frontal cutting element has the advantage that the rearwarddeflection of the chain 21 is reduced.

The chain 21 is coupled to the cutting head 2 by means of pivot links,pivotally mounted on a pivot shaft 106 of the central part 11 of thecutting head 2. The central part 11 has a circumferential sleeve 108 inwhich the chain 21 can be rolled up. The sleeve 108 extends between twocircumferential flanges 104, 109, which are of such height that thechain 21 can be fully accommodated in the sleeve 108 in between them. Inthis way, the chain 21 is a collapsible cutting element, which cancollapse into the sleeve 108 for being moved past obstacles Q on theinterior wall W of the pipe which is cleaned. Such an obstacle may forexample result from a level difference between subsequent pipe sections.Once the chain 21 is moved past the obstacle Q, the chain 21 is againextended from the sleeve 108 as a result of centrifugal forces.

As is further shown in FIG. 1, the body 111 of the device 1 comprisessupport means 112 for supporting the body 111 carrying the cutting head2 on the pipe wall W. These support means are formed by arrays 112 ofcollapsible support elements 30. The device 1 of FIG. 1 comprises threesuch arrays 112, of which one is shown. The three arrays are provided atregular distances from each other around the circumference of the body.Each array 112 comprises five collapsible support elements 30. The bodymay however also comprise any other number of arrays 112 with any numberof collapsible support elements 30 deemed suitable by the person skilledin the art.

Each collapsible support element 30 comprises a wheel 31, an L-shapedarm 34 and a pull spring 33. The wheels 31 are mounted in a planeextending through the central axis H of the device 1, so substantiallyperpendicular to the pipe wall W. Each wheel 31 is rotatably mounted onits arm 34. The arm 34 is pivotally mounted on the body 111 and has apivot axis 113 which is offset from the rotation axis of the wheel 31 inlongitudinal direction of the device. This offset ensures that thesupport element 30 can collapse, by rotating the wheel 31 away from thepipe wall W when encountering an obstruction Q. For the front supportelements 30 located at the cutting head 2, the offset is backwards,i.e., the rotation axis of the wheel 31 is behind the pivot axis 113.For the rear support elements 30, the offset is forwards. In this way,the movability of the device 1 in both forwards and backwards directioncan be ensured. The pull spring 33, which extends in line with theL-shaped arm on the opposite end of the pivot axis 113 with respect tothe end on which the wheel 31 is mounted, is provided for pressing thewheel 31 back onto the pipe wall W past the obstruction Q. By thisconstruction, the device 1 can easily be moved past a narrower part inthe pipe, without losing the support on the pipe wall W: when onesupport element 30 collapses, its supporting function is temporarilytaken over by the other support elements 30 of the array 112. Theresiliency of the springs 33 is predetermined, for achieving that thesupporting capacity of the whole array is sufficient for stillsupporting the body if at least one support element 30 is collapsed. Ascan be understood from FIG. 1, the support elements can also allcollapse towards either the front end or the rear end of the device.

The body 111 may further be adjustable, so that the distance between thearrays 112 of collapsible support elements can be adjusted and thedevice 1 can be adjusted to the diameter of the pipe which is to becleaned.

The pressurised liquid which is used for driving the rotation of therotor 4 and for propelling the device 1 in forwards direction Z throughthe pipe is preferably water. The device 1 is propelled forwards bymeans of the reaction forces of one or more propulsion jets (not shown).Evidently, the forwards propulsion can be achieved with any otherpropulsion means known to the person skilled in the art.

1. A pipe-cleaning device comprising: a cutting head for cutting awaymaterial on the interior of a pipe, a body on which the cutting head isrotatably mounted, and drive means for driving the rotation of thecutting head with respect to the body, wherein the body has acircumference where a plurality of arrays of collapsible supportelements extending in a longitudinal direction of the body are mountedfor supporting the body on an interior (W) of a pipe, wherein thecutting head includes one or more collapsible cutting elements whichextend in a radial direction of the cutting head and are inwardlycollapsible with respect to the circumference of the body; wherein thebody has a front end at which the cutting head is mounted and a rear endopposite the front end; and wherein the collapsible support elements aremounted to be inwardly collapsible with respect to the circumference ofthe body against the action of a resilient member, the collaosiblesupport elements at the front end being collapsible towards the rear endand the collapsible support elements at the rear end being collapsibletowards the front end.
 2. The pipe-cleaning device according to claim 1,wherein each collapsible support element comprises a wheel which isrotatably mounted about a rotation axis on a collapsible arm, the armbeing pivotally mounted about a pivot axis on the body, the rotationaxis being offset from the pivot axis in longitudinal direction of thebody.
 3. The pipe-cleaning device according to claim 2, wherein theresilient member is a pull spring which extends in line with thecollapsible arm in an unloaded state.
 4. The pipe-cleaning deviceaccording to claim 1, wherein by at least three arrays of at least threecollapsible support elements, the arrays being located at regularlocations on the circumference of the body.
 5. The pipe-cleanin deviceaccording to claim 1, wherein the cutting head comprises at least onefirst collapsible cutting element which extends radially from a rigidcentral part, each first collapsible cutting element ending in a firstcutting block and being provided with at least one mass increasingelement at an intermediate location between the central part and thefirst cutting block.
 6. The pipe-cleaning device according to claim 5,wherein each mass increasing element is formed by a second cuttingblock.
 7. The pipe-cleaning device according to claim 5, wherein thefirst collapsible cutting element comprises a first chain part from thefirst cutting block to the mass increasing element and a second chainpart from the mass increasing element to the central part, the firstchain part having a weight which is smaller than or equal to that of thesecond chain part.
 8. The pipe-cleaning device according to claim 5,wherein the cutting head further comprises at least one secondcollapsible cutting element in front of the at least one firstcollapsible cutting element, each second collapsible cutting elementbeing of equal length or shorter than each first collapsible cuttingelement.
 9. The pipe-cleaning device according to claim 8, wherein eachsecond collapsible cutting element comprises a third chain part endingin a third cutting block, the third chain part being of substantiallyequal length with the second chain part of the first collapsible cuttingelements.
 10. The pipe-cleaning device according to claim 5, wherein atleast one of the first, second and/or third cutting blocks is providedwith a cutting protrusion which extends in forwards direction from thecutting block.
 11. The pipe-cleaning device according to claim 1,wherein the drive means comprises a stator and a rotor which isrotatably mounted on the stator about a rotation axis, the stator havingat least one nozzle connected to a supply duct for directing a liquidstream of a pressurised liquid supplied via the supply duct successivelyonto a plurality of drive elements of the rotor, wherein the at leastone nozzle extends substantially within a plane (V) perpendicular to therotation axis of the rotor and that the at least one nozzle is locatedinwardly from the rotor.
 12. The pipe-cleaning device according to claim11, wherein each drive element of the rotor has a drive plane forperiodically receiving the liquid stream, the drive plane being directedsuch that the liquid stream is received in a substantially perpendiculardirection (P).
 13. The pipe-cleaning device according to claim 12,wherein the drive elements during operation travel along a circular pathand each drive plane is directed in an angle a of 20-70 ° with respectto this circular path.
 14. The pipe-cleaning device according to claim13, wherein each nozzle is directed in an angle p of 45-90 ° withrespect to the circular path of the drive elements.
 15. Thepipe-cleaning device according to claim 12, wherein each drive elementhas a leading edge which is rotated first into the liquid stream of thenozzle during operation, the leading edge being bevelled in a directiontowards the drive plane of the in rotation direction previous driveelement of the rotor.
 16. The pipe-cleaning device according to claim15, wherein the distance (x) between the nozzle and the leading edge ofthe drive elements is within the range of 1-5mm.
 17. The pipe-cleaningdevice according to claim 1, wherein all of the collapsible supportselements are collapsible both towards the rear end and towards the frontend.